Thermoplastics have a wide variety of uses. This is generally due to their processing ease, making it possible to mold difficult or intricate shapes fairly easily. Unfortunately some thermoplastics tend to be brittle. Thus, they tend to break on impact. One of the methods to improve the toughness of thermoplastics is to incorporate therein small amounts of a dispersed rubbery phase. This has resulted in materials such as high impact polystyrene (HIPS). This type of tough polymer may be prepared by grafting a thermoplastic onto a rubbery polymer during polymerization of the thermoplastic. Such procedures are well known to those skilled in the art.
It is also possible in some circumstances to physically blend thermoplastics and impact modifiers. Representative of such blending art are U.S. Pat. Nos. 4,172,859 and 4,174,358 to Epstein. However, if the rubbery phase is not compatible with the thermoplastic, there will not be an enhancement of the properties of the thermoplastic, in fact, the impact properties may likely decrease.
It is known that tertiary amines will react with halogens to produce a quaternary amine. U.S. Pat. No. 4,355,139 issued Oct. 19, 1982 to Coran et al assigned to Monsanto discloses a compatibilizing blend of a functionalized poly alpha olefin and an amine modified nitrile rubber. The disclosure of the Coran patent illustrates a tertiary amine linkage at Col. 3. The chlorine from the olefin reacts with an amine in the nitrile rubber. This does not suggest the butyl rubber impact modifiers of the present invention.
It is known that halobutyl rubber in admixture with amine containing compounds has good "green" strength. This is disclosed in U.S. Pat. No. 4,256,857 issued Mar. 17, 1981 to Buckler et al, assigned to Polysar Limited. The Buckler patent does not suggest that such halobutyl rubber could be used as a toughening agent for thermoplastics.
The present invention seeks to provide novel compositions of thermoplastics toughened with halogenated butyl rubber.